Semen Analysis and Physiology

Semen Analysis

• Semen analysis is vital for assessing fertility, particularly for couples delaying parenthood and those using assisted reproductive technology (ART).
• Routine semen analysis is often performed in clinical labs, and abnormal results may lead to further testing in specialized andrology labs to determine suitability for in vitro fertilization (IVF).

Physiology of Semen Production

• Testes: Paired glands in the scrotum, crucial for sperm production. Their external location maintains optimal lower temperature for sperm development.
• Seminiferous Tubules: Sperm production begins within the seminiferous tubules. Sertoli cells support and nourish germ cells during mitosis and meiosis (spermatogenesis).
• Epididymis: Immature sperm complete maturation and develop flagella in the epididymis before storage until ejaculation.
• Vas Deferens: Sperm are propelled through the vas deferens to the ejaculatory ducts.
• Seminal Vesicles: Produce the majority of seminal fluid (approximately 60-70%). The fluid contains fructose and flavins as a transport medium for the sperm. The fructose provides energy to the sperm.
• Prostate Gland: Located below the bladder, surrounds the upper urethra to propel sperm through the urethra via muscular contractions. It also produces acidic fluid (approximately 20-30% of the volume). The acid fluid contains enzymes (acid phosphatase, citric acid, zinc) for coagulation and liquefaction of the semen.
• Bulbourethral Glands: Contribute to lubrication and a more alkaline environment (approximately 5% of the volume). The alkaline mucus neutralizes vaginal acidity, aiding sperm motility.
• Absence of Fructose: Crucial for proper sperm motility, without it, sperm will not demonstrate motility in the analysis.
• Flavin in Semen: Responsible for the gray appearance, and important for assessing the semen.

Semen Production

• Semen production starts with the epithelial cells in seminiferous tubules. Nutrients for spermatogenesis supplied by Sertoli cells support and nourish germ cells during spermatogenesis.
• Immature sperm enter the epididymis for maturation and development of flagella. Sperm are stored there until ejaculation.
• Once ready, sperm are moved through the vas deferens to the ejaculatory ducts.

Specimen Collection

• The first ejaculate contains most of the sperm.
• Complete collection is vital to avoid falsely decreased sperm count or altered pH.
• Uncollected last portion of ejaculate causes falsely increased sperm count and an altered pH.
• Collection of 2 or 3 samples (spaced by no less than 7 days or more than 3 weeks) is advised, collected in a warm sterile container (glass or plastic) via masturbation.
• Non-lubricated condoms (polyurethane or rubber) can be used if needed.
• Specimens should arrive within 1 hour of collection.
• The period of sexual abstinence should be recorded.
• Standard precautions (as semen is a potential reservoir for HIV) should be observed during handling.

Semen Analysis Parameters

• Appearance: Normal-gray-white, translucent, characteristic musty odor. Abnormal - appears almost clear due to low sperm concentration, or increased white turbidity.
• Volume: 2ml to 5ml is normal. Decreased volume is associated with infertility.
• Viscosity: Droplets that form longer threads than 2 cm indicate abnormal viscosity; Ratings 0 - watery, 4 – gel like.
• pH: Prostatic fluid is acidic, seminal vesicle fluid is alkaline. Normal pH range is 7.2-8.0.
• Sperm Concentration & Count: Normal range: 20 million/ml to 250 million/ml (Borderline: 10-20 million/ml).
• Sperm Motility: Measured with 0–4 grade. 0-no movement, 4-rapid straight line movement.. minimum 50% motility with a rating of 2.0 after 1 hr is considered normal.
• Sperm Morphology: Assessing sperm shape and size. Normal parameters include morphology with > 14/ >30% normal forms (strict/routine criteria).
• Microscopic Examination: WBCs differentiation from immature sperm. Red discolorations of RBCs present and considered abnormal. Yellow from urine is toxic to sperm.

Liquefaction

• Fresh semen should coagulate and liquefy within 30-60 minutes following collection. Failure to liquefy within 60 minutes requires reporting. Examination should be performed after liquefaction has occurred.
• Add alpha-chymotrypsin or bromelain to induce liquefaction if necessary, within 2 hours of collection.

Additional Testing for Abnormal Results

• Further testing is advised for cases with abnormal semen analysis, including:
  • Vitality: Eosin-nigrosin stain used to evaluate the proportion of living sperm.
  • Seminal Fructose: Resorcinol test to determine the presence of fructose.
  • Antisperm Antibodies (ASA): Used to detect presence of antibodies in male and female subjects through Mixed Agglutination Reaction (MAR) or Immunobead test.
  • Microbial Testing: Determining if possible factors are contributing to abnormalities (e.g., Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum).
  • Rape cases: Detecting seminal fluid using prostatic acid phosphatase or seminal glycoprotein p30 (prostatic specific antigen)

Postvasectomy Semen Analysis

• Assess the presence or absence of spermatozoa.
• Routinely test at 2-month intervals post-vasectomy for complete sterilization confirmation.
• Examine wet and centrifuged specimens.